After the development of the first version of our high-power lithium ion battery in 2000, we have been further improving its performance, such as the power and life. Our recent progress in the development on the new version (Gen 2) battery is presented. The prolonged cycle life test at 50 degrees C reached 900,000 cycles with a 50% increase in the direct current resistance (DCR), and the storage life test at 50 degrees C over 1 year showed a 20% increase in the DCR. These life test data suggested a much longer calendar life in real applications than our former lithium battery version. A new 48-cell module was developed, and it proved to have a high-power capability and good cold cranking performance as expected by the cell performance. (c) 2007 Published by Elsevier B.V.